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I wrote a custom combobox server control that inherited the webcontrols.listbox class so that I'd get all of the built-in list handling features. Then I added a textbox to allow me to type in a value that wasn't in the listbox, and some client-side javascript to set the textbox to the selected item in the list when one was clicked, select a matching item in the list when one was typed into the textbox, or to set the list's selectedIndex to -1 when the value typed into the textbox didn't match. All of this works fine.
The problem is that when the form posts back I don't see any of the data I expected, not the list selection, nor the textbox value.
As I said I expected the list selection to be returned automatically, but I didn't actually use that instance, opting instead to use a span container with the a textbox, another listbox, and an imagebutton added to the span's controls, then rendered from the span level. So, how do I get the data to post-back from these sub-controls?
I really don't want to use the original list that my control inherited, as I need the span container to make my control work in absolute position mode. However, to make my control work in non-absolute position mode, when the textbox's width is set to auto, I don't always render the span, instead I simply render the controls below the span and let the browser work out all of the widths.
Thank you in advance.
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Using the following code I can see my data:
Dim CBX1 As cwcComboBox.cwcComboBox = Me.cwcComboBox1
Dim CBX1Value As String
Dim CBX1Values As String()
CBX1Value = CBX1.Page.Request.Params.Get(CBX1.ID)
CBX1Values = CBX1.Page.Request.Params.GetValues(CBX1.ID)
CBX1Value = "Three,3", CBX1Values(0)="Three", and CBX1Values(1)="3"
So the data is there. However, when I try to access the data the "correct" way by declaring a LoadPostData function as follows:
Public Function LoadPostData( ByVal Key As String, ByVal PostData As NameValueCollection ) As Boolean _
Implements IPostBackDataHandler.LoadPostData
:
End Function
The compiler says that IPostBackDataHandler is not implemented by this class, but my custom component inherits from the ListBox webcontrol. So at the top of my class, after the inherits statement, I tried using:
Implements System.Web.UI.IPostBackDataHandler
But the compiler says its already implemented by the listbox base class, which seems to disagree with the earlier compiler error!
Anyone know what's going on with this?
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Here is an important missing piece that needs to be added after the inherits statement:
Implements INamingContainer
Now I no longer get the conflicting messages, only one that says:
'System.Web.UI.IPostBackDataHandler.LoadPostData' is already implemented by base class 'System.Web.UI.WebControls.ListBox' and cannot be implemented again.
So now my question is how do I override or shadow the one in the base class so I can capture the rest of the data that my component sends back?
My component is a combobox, and should send back the TextBox value and the ListBox Index.
Even if getting the LoadPostData to work, it isn't clear to me how you get both of these data values out of it. The example code I've seen so far says that the Key value is the name of my component, which is used as an index in the NameValueCollection paramenter, so it seems to only be set up to get one value.
Also, since I have two values, which one will it get?
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Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
MyBase.OnInit(e)
Try
If Page.IsPostBack() Then
' The page can have many instances of this component, so don't want to push the
' cwcComboBoxInfo state class instance infomation through the ViewState, so put
' a reference to in a session variable, actually done at the end of the Render
' Sub.
'
' When the page is posted back, the component state is restored by setting the
cwcComboBoxInfo to the reference value saved in the session variable.
'
If Not HttpContext.Current.Session(cwcComboBoxInfo.ID) Is Nothing Then
cwcComboBoxInfo =
CType(HttpContext.Current.Session(cwcComboBoxInfo.ID),
cwcComboBoxInfoClass)
End If
' Get the postback data.
LoadPostData() ' There is a bug in VS.NET 2003 that prevents the LoadPostData
' function from overriding/shadowing the listbox base class's
' IPostBackDataHandler.LoadPostData and RaisePostDataChangeEvent
' implementation, so call the LoadPostData function directly to
' get the posted data.
End If
Catch Ex As Exception
Throw New cwcComboBoxException("OnLoad: Exception - Component " & Me.ID & ", " & _
Ex.Message)
End Try
End Sub
' -------------------------------------------------------------
' The following was a suggested fix to the IPostBackDataHandler implmentation problem, but
' it didn't seem to help. Instead, Sebastián Streiger suggested that the Impments ...
' statement should be removed from the LoadPostData function and RaisePostDataChangeEvent Sub
' declarations. However, while this allowed me to compile the code it doesn't seem to get
' called by the .NET Framework. So I implmemented a override LoadPostData function with no
' parameters that I directly call from the OnLoad event sub above.
Public Shadows Interface IPostBackDataHandler
Function LoadPostData(ByVal sPostData As String, _
ByVal oPostCollection As NameValueCollection) As Boolean
Sub RaisePostDataChangedEvent()
End Interface
' -------------------------------------------------------------
Private Enum EventsType
NoEvent
TextBoxValueChanged
SelectedListIndexChanged
End Enum
'
' This "global variable keeps track of the component's event that needs to be raised.
' Part of the IPostBackDataHandler workaround I'm using.
'
Private EventType As EventsType = EventsType.NoEvent
'
' Define a LoadPostData function that can be called from the OnLoad event
' just in case the IPostBackData Handler isn't called by the .NET Framework.
'
Private Function LoadPostData() As Boolean
Return LoadPostData(cwcComboBoxInfo.ID, Me.Page.Request.Params)
End Function
'
' Should be called by the .NET Framework do allow handling of the PostBack Data for this
' component. If that doesn't happen then the overload above can be called.
'
Public Overridable Function LoadPostData(ByVal Key As String, _
ByVal PostedValues As NameValueCollection) _
As Boolean
'
' Implements System.Web.UI.IPostBackDataHandler.LoadPostData
'
Dim Values As String() = PostedValues.GetValues(cwcComboBoxInfo.ID)
Dim OldValue, NewValue As String
Dim Result As Boolean
Select Case Values.Length
Case 0
' Use the component's custom exception
EventType = EventsType.NoEvent
Throw New cwcComboBoxException("LoadPostData: Exception - " & _
"No data found for the '" & _
cwcComboBoxInfo.ID & "' component!")
Case 1
OldValue = [Text]
NewValue = Values(0).Trim()
If [IgnoreCase] Then
Result = (OldValue.ToLower() = NewValue.ToLower())
Else
Result = (OldValue = NewValue)
End If
If Result Then
[SelectedListIndex] = NOTHINGSELECTED
[Text] = NewValue
EventType = EventsType.TextBoxValueChanged
End If
Case 2
[SelectedListIndex] = Val(Values(1))
EventType = EventsType.SelectedListIndexChanged
Case Else
EventType = EventsType.NoEvent
Throw New cwcComboBoxException("LoadPostData: Exception - Too much data " & _
"posted for the '" & _
cwcComboBoxInfo.ID & "' component, " & _
Values.Length & " data items " & _
"(" & Me.Page.Request.Params.Get( _
cwcComboBoxInfo.ID) & ")!")
End Select
Return (EventType <> EventsType.NoEvent)
End Function
' -------------------------------------------------------------
Public Event TextBoxValueChanged As EventHandler
Protected Overridable Sub OnTextBoxValueChanged(ByVal Ex As EventArgs)
RaiseEvent TextBoxValueChanged(Me, Ex)
End Sub
' -------------------------------------------------------------
Public Event SelectListIndexChanged As EventHandler
Protected Overridable Sub OnSelectedListIndexChanged(ByVal Ex As EventArgs)
RaiseEvent SelectListIndexChanged(Me, Ex)
End Sub
' -------------------------------------------------------------
Public Overridable Shadows Sub RaisePostDataChangedEvent()
'
' Implements IPostBackDataHandler.RaisePostDataChangedEvent
'
' Figures out which event handler to use.
'
Select Case EventType
Case EventsType.NoEvent
' No Action - No event occurred.
Case EventsType.TextBoxValueChanged
OnTextBoxValueChanged(EventArgs.Empty)
Case EventsType.SelectedListIndexChanged
OnSelectedListIndexChanged(EventArgs.Empty)
End Select
End Sub
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I have a table with some cells containing span tags that I use to display text values that my javascript code populates and that the user may not change. Other cells in this table contain input text boxes, which the user may change. And before cells containing a span or text box, I have a cell that contains the title of the data displayed in the adjacent cell.
I want both the text boxes and the contents of the spans to be left aligned, and the titles to be right aligned, so I tried using the following CSS style decleration placed before the table elments I want justified:
<style>
span { text-align:left }
table tr td { text-align:right }
</style>
This works well for the input boxes, which are normally left justified and aren't affected by the above style settings, and the titles, but not for the span contents.
Why doesn't the span selector seem to work?
What do I need to do to make the text in the spans left justify?
Thank you
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HTML has two types of elements, inline and block. <span> is inline element, and <td> is a block element. Inline elements do not have height or width. Thus, text alignment within such an element will not have any affect.
"We make a living by what we get, we make a life by what we give." --Winston Churchill
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Thank you for replying.
So if I understand you, the span nested in side of the table cell is being treated as an inline element, so ignores the text-alignment of the cell, but because it is an inline element also ignores any text-align-ment that I try to force on it with the CSS Style settings.
Therefore, since the span'ed cells show on the right side of the cell, it must be the entire span that's being pushed over there by the table tr td CSS style selector.
Correct?
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howardjr wrote: So if I understand you, the span nested in side of the table cell is being treated as an inline element, so ignores the text-alignment of the cell, but because it is an inline element also ignores any text-align-ment that I try to force on it with the CSS Style settings.
No, the span element and the the text's alignment is controlled by the td element's alignment. The default behavior of the span element does not respond to the CSS text-alignment.
howardjr wrote: Therefore, since the span'ed cells show on the right side of the cell, it must be the entire span that's being pushed over there by the table tr td CSS style selector.
Yes.
"We make a living by what we get, we make a life by what we give." --Winston Churchill
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Thanks again 
I put back in align="right" into the td tags that I took them out of in favor of the style selector table tr td as it seemed as much trouble to put in a css class as it was to just use the align="right". Anyway, now I understand a this a bit more, to for that much this was good.
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FYI, CSS1 didn't really support tables well. However, CSS2 has rectified that. You could have applied styles to the td elements using class attributes. Thus, you could alternate text alignment just by changing the class attribute.
"We make a living by what we get, we make a life by what we give." --Winston Churchill
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True,
Therefore I would make one class for my data label cells and one for the data cells, which would make it clear to anyone looking at my HTML code what was being displayed in each type of column. But the point of my comment was that it would take as much typing to say align="right" in the label cell's td tags and nothing in the data cell tags as it would to create the classes and use them. The intent of my page is to display and change the dynamic HTML attributes so I can see how they work, so self-documenting isn't that important to me in this page. However, the lessons learned about using CSS classes on different tag items is.
Thanks again.
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i found something strange in the IE with the javascript
and here is the case:
open this code with firefox and you shall see this character: (<)
and then try it on IE and you will see nothing.
the ie (i think) doesn't know this hexa, if you change it to other like 0x003A ,B or D...it will work fine...but not C
--------------------------------------------------------------------------------------
<html>
<head>
</head>
<body>
<div id="test">123</div>
<script language="javascript1.2" type="text/javascript">
document.getElementById("test").innerHTML = String.fromCharCode("0x003C");
</script>
</body>
</html>
----------------------------------------------------------------
why? and what is the solution?
Faris Madi
Nothing Comes Easy (N.C.E.)
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too close to W3c?
Brad
Australian
"Keyboard? Ha! I throw magnets over the RAM chips!" - peterchen
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what you mean too close
Faris Madi
Nothing Comes Easy (N.C.E.)
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That was a joke,
the W3c (World Wide Web Consortium) are the people who set the standards for many web protocols (such as html etc.).
As you may have noticed, IE seems to have a thing for not doing what they say.
Brad
Australian
"Keyboard? Ha! I throw magnets over the RAM chips!" - peterchen
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Bradml wrote: As you may have noticed, IE seems to have a thing for not doing what they say.
Cross browser compatability is like trying to heard cats! They all have a different agenda.
I'm on-line therefore I am.
JimmyRopes
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You are putting illegal html code in the innerHTML property. The browser may choose to handle this error any way that it likes. IE chooses to ignore the broken code, while Firefox chooses to convert it to plain text.
---
It's amazing to see how much work some people will go through just to avoid a little bit of work.
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if this is an illegal code...
so how can be this code run on IE:
document.getElementById("test").innerHTML = String.fromCharCode("0x003D");
and this is not:
document.getElementById("test").innerHTML = String.fromCharCode("0x003C");
????
Faris Madi
Nothing Comes Easy (N.C.E.)
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Because "=" is valid html, and "<" is not.
---
It's amazing to see how much work some people will go through just to avoid a little bit of work.
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I get it.
i made and escape function that comverts the illegal characters to other format like & to & ..etc
Faris Madi
Nothing Comes Easy (N.C.E.)
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I'm sure this question has been asked a million times, but it's new to me since I haven't done any web development lately.
Anyway, does anyone know of a good CSS compliant way of having a real footer (ie, doesn't overlap the content) on a web page that works on all browsers including Opera?
On Firefox using divs makes the document overlap and using tables don't seem to do anything at all. I'm starting to feel like a dinosaur here.
And, I just have to get this off my chest.  This used to be so easy in HTML. Sure, there wasn't standardized way, but it worked in all browsers minus a few quirks. This XHTML thing seems to be a case one step forward and two steps back.
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Hey Jeremy,
There are a couple of ways to do this. It really depends on how the page is structured. If you have a page that just flows (like standard html) then you simple place a div at the base of the document containing the footers.
This works fine for basic layouts, but other times you are going to need to have it positioned as part of the layout. The next method applies if you are using the "position:absolute" (or its subs) css... thing. You have to build the footer into the page. This can be really annoying but you have to position the rest of your divs so that they take into account that the footer is there. (Just btw to position something on the bottom use this: "position:absolute; bottom:0px;").
There are many other ways of doing this, but without seeing how you structure your code I could only offer abstract advice.
And as for your remarks about Xhtml, it is not the problem we are all facing. The main difference we face with Xhtml is that we have to be more careful with nested tags. CSS is the real problem as we are not able to create a single style sheet that is cross browser without spending many hours testing and using obscure hacks that mean we have to go back next time a browser is released and completely re-write that back of the sheet.
Web development has hit a dark patch as standardization is far from being obtained, and people still continue to use older browsers that we have to compensate for.
The only way standardization will be achieved is if web masters decide to shun no compliant agents (which will never happen). So I've been toying with a new web protocol that will serve exclusively to compliant agents (not that it will ever take off).
Ok well I hope that the answer to your question is somewhere in there,
Regards,
Brad
Brad
Australian
"Keyboard? Ha! I throw magnets over the RAM chips!" - peterchen
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Howdy.
The problem I faced with absolute positioning is it will overlap the other divs when the browser is resized small enough. Also, the main reason I say it's XHTML that's driving me crazy is that it enforces the rule about not caring for the height attrib to a table whereas in HTML you could take advantage of that if CSS wasn't playing fair.
Anywho, seeing that I speak HTML better than XHTML, lemme show you the layout I'm going for with the old school way of things...
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<body leftmargin="0" topmargin="0" rightmargin="0" bottommargin="0" marginwidth="0" marginheight="0">
<table width="100%" height="100%" cellspacing="0" cellpadding="0" border="1">
<tr>
<td>1</td>
<td>2</td>
</tr>
<tr>
<td>3</td>
<td>4</td>
</tr>
<tr>
<td colspan="2" valign="bottom">5</td>
</tr>
</table>
</body>
</html>
Basically I always want cell 5 to act as the footer on the bottom but also have it never overlap. TIA btw.
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Jeremy Falcon wrote: Also, the main reason I say it's XHTML that's driving me crazy is that it enforces the rule about not caring for the height attrib to a table whereas in HTML you could take advantage of that if CSS wasn't playing fair.
The table tag doesn't have a height attribute at all, it never has and it never will. It's only Internet Explorer that thinks that it has.
The reason that Internet Explorer ignores the heigth attribute when you are using XHTML, is that then it tries to follow the standards and treats it correctly.
---
It's amazing to see how much work some people will go through just to avoid a little bit of work.
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Guffa wrote: The table tag doesn't have a height attribute at all, it never has and it never will. It's only Internet Explorer that thinks that it has.
I never said it was. For that matter, every browser in the world still reads the height attribute for tables in quirk-mode for HTML rendering, this is not just for IE. My point was XHTML is more strict and thus it won't allow it but you always could in HTML even if it wasn't a standard. The only real problem was the calculations different browsers used to determine the final height.
Guffa wrote: The reason that Internet Explorer ignores the heigth attribute when you are using XHTML, is that then it tries to follow the standards and treats it correctly.
Thanks for the reply, but I think most people that can get past "beginner's XHTML" already know this.
When standardizing XHTML, the geniuses behind it should've realized HTML was never used for what it was intended by the time it got popular. Its usage evolved and as such, core functionality should have done so too. Instead, when making a standard they take something that used to be simple and wipe it away - never mind the fact that CSS can really suck at times when it comes to positioning and compatibility.
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